As it has just become official, an army of millions of transgenic mosquitoes has fulfilled its mission more than satisfactorily in Piracicaba, a town in Brazil affected by dengue, a fever that affects 1.5 million people in that South American country. The “effective” were genetically modified males of the Aedes aegypti species, whose bite spreads not only the dengue virus, but also the pathogens of other diseases such as chikungunya, yellow fever and the much feared Zika . That was why there was so much interest in knowing how the experience had turned out.
Created by the British company Oxitec, the modified specimens incorporate a fatal gene that they transmit to the females with whom they mate. Due to this mutation, the offspring are unable to reach the adult stage and thus the Aedes aegypti population progressively decreases until it is eradicated.
According to reports, the number of people affected by dengue in the Piracicaba area where the transgenic males were scattered – the Cecap-Eldorado neighborhood – decreased by more than 90% . Previous trials had already shown that this technique decimated the wild mosquito population , but now the first clear evidence has been obtained that it also dramatically reduces the incidence of the disease.
Currently, the Oxitec company is working with the World Health Organization to carry out larger trials, since only 5,600 people live in Cecap-Eldorado . Apart from its effectiveness, another advantage of this method is that, unlike insecticides, it has no impact on the environment. Although it also has an important downside: its economic cost. For example, to combat dengue in the Piracicaba neighborhood where the test was carried out, it was necessary to release between three and four million mosquitoes per month .
